This page actually points out a minor frustration that I frequently experience with UTM in GIS software and GPS receivers, under the "MGRS grid row designators".<p>These MGRS row designators are completely optional and redundant, because a UTM northing values span the entire Y dimension of a Zone.<p>What is <i>not</i> redundant is the hemisphere designator, "N" or "S".<p>There are 20 row designators, and the designers excluded the letters "I" and "O" to avoid confusion with the visibly-similar numbers "1" and "0". There are 26 letters in the alphabet to choose from, but they did <i>not</i> bother to exclude the letters "N" or "S".<p>It just so happens that the row which covers half of the continental United States - which is in the <i>Northern</i> hemisphere - is the row labeled "S".<p>So well-meaning GIS software and even Garmin GPS receivers often call my zone "17S", which reads as "Zone 17, Southern Hemisphere". My zone is in fact "17N", "Zone 17, Northern Hemisphere". This is especially annoying given that the row label is an artifact of MGRS and not civilian UTM.<p><a href="http://www.mibsar.com/LandNav/UTM/UTM.htm#Rows" rel="nofollow">http://www.mibsar.com/LandNav/UTM/UTM.htm#Rows</a>
> Every UTM grid is perfectly square and exactly the same size. All UTM coordinate grids are perfectly square and exactly the same size — 1,000 meters by 1,000 meters — across the entire grid system.<p>Since the Earth does in fact <i>not</i> have a circumference that's a integer multiple of 1 km, does this mean this projection just leaves out some sliver of the Earth's surface?<p>East to west its not too bad, just 17 metres off, but north to south that's over 800 meter of extra surface to hide!